The invention relates to an electronic thin-film component comprising a substrate, electrode layers for the bottom electrode, top electrode and, optionally, one or more intermediate electrodes, and comprising functional intermediate layers, said electrode layers including electroconductive, oxidic compounds.
Such components can be discrete components or multifunctional, multi-component systems, such as non-volatile ferro-electric memories, dynamic random-access write-read memories, integrated capacitors, thin-film actuators, thin-film resistors, piezo-electric sensors, piezo-electric transducers, pyroelectric sensors, electro-optic components or modules comprising integrated passive components (ICM).
For example, for applications in non-volatile ferro-electric memories, piezo-electric transducers, sensors and actuators as well as pyroelectric sensors, functional layers of perovskites of the composition PbZr.sub.x Ti.sub.1-x O.sub.3, wherein x=0.3-0.7, as well as Pb.sub.1-1.5y La.sub.y Zr.sub.x Ti.sub.1-x O.sub.3, wherein y=0.3-0.07, x=0.4-0.6, and Pb.sub.1-1.5y La.sub.y TiO.sub.3, wherein y=0.05-0.16, are stacked between electrodes. High-frequency modules for filtering applications in accordance with the state of the art, comprising capacitors and resistors include combinations of SiO.sub.2 and Si.sub.3 N.sub.4 as the functional layers.
In these and other thin-film components, platinum is used as the electrode material, which is preferred to other electrode materials, such as Cu, Al or Ag/Pd, to preclude reactions of the electrode material with the material of the functional layers, for example perovskites, when said material is sintered during its manufacture in an oxygen atmosphere at 600-800.degree. C. However, connecting the platinum electrode to the substrate is problematic. In order to obtain a good adhesion of the Pt electrode layers to a customary substrate, such as silicon with SiO.sub.2 insulating layers, an adhesive layer, for example a thin Ti layer must additionally be provided as an intermediate layer between Si/SiO.sub.2 and Pt. Also in the case of optimized electrode layers and adhesive layers, the adhesion of the Pt electrodes after sintering of the perovskite layers is often insufficient. As a result, the entire capacitor assembly including the bottom electrode becomes detached from the substrate during the post-treatment. This is the reason why for many applications high-reliability components can yet not be manufactured.
Apart from the integration of perovskite layers in semiconductor ICs, for example, for integrated capacitors, ferro-electric, non-volatile memories or random-access write-read memories, as well as for pyroelectric and piezo-electric components, perovskite layers are also used in the manufacture of modules comprising integrated passive components. In these modules, the perovskite layers are used as dielectrics in thinfilm capacitors and are deposited between electrodes, such as Pt electrodes. Also in this application, the poor adhesion of platinum layers to substrate materials, such as Si/SiO.sub.2 or Al.sub.2 0.sub.3 and to functional layers, such as oxidic perovskite layers comprising Pb.sub.1-1.5y La.sub.y Zr.sub.x, Ti.sub.1-x O.sub.3 wherein 0.53&lt;x&lt;1 and y=0.05-0.15 or Pb(Mg, Nb).sub.x Ti.sub.1-x,O.sub.3, wherein 0.65&lt;x&lt;1 is clearly a disadvantage.
A further disadvantage of the Ti/Pt electrode layers resides in that this material system can only be deposited by means of vacuum techniques, such as cathode-ray sputtering or electron-beam evaporation. Said methods, however, involve high investments as well as high operating costs as, for example in the case of a cathode ray process, expensive Pt targets must be purchased.
Perovskite layers, such as PbZr.sub.x Ti.sub.1-x O.sub.3, wherein x=0.2-0.7, on Si substrates with a Ti adhesion layer and a Pt layer as bottom electrode as well as a Pt layer as the top electrode are used in a new type of memories, i.e. ferro-electric non-volatile memories. A plurality of investigations have revealed, however, that such ferro-electric memory cells demonstrate, dependent upon the deposition conditions, a greater or smaller degree of fatigue. The switched charge of such ferro-electric memory cells decreases clearly after several hundred switching cycles, as a result of which such memory cells are no longer functional. Although the phenomena responsible for the occurrence of fatigue in these materials are so far unknown, other electrode materials in combination with the known functional layers must be used to eliminate this fatigue.
To overcome this disadvantage, EP-A-0 495 114 proposes a semiconductor component on which a ferro-electric film, forming an active element on a semiconductor substrate, is integrated by means of electrodes which form a laminar structure with the ferro-electric film, one or both of the electrodes forming the laminar structure being an oxidic conductor which is predominantly composed of either ITO (mixed crystal of indium oxide and tin oxide), ruthenium oxide, rhenium oxide, tungsten oxide, chromium oxide or molybdenum oxide. These oxide electrodes are manufactured by means of sputtering. Apart from the ITO layer, these oxide layers are very brittle and, partly, ill conducting.